POS Form, Checkout Form and Crypto Class

Changes:
* POS
- Added Refund Buttons and Rearranging the Barcode Search Button
- Changes in the Shortcut Key
* Checkout Form
- Changes in the naming convention to some objects
* Crypto Class
- Added AES Code Encryption for Storing Debit Cards and Credit Cards
Number.

Note: I already formulated the Printing Receipt for nPOS. The Codes is
ready in a jiffy.